Since the public launch of Large Language Models (LLMs), we have been studying how artificial intelligence (AI) impacts performance on complex and knowledge-intensive tasks. In a joint experiment with Boston Consulting Group, 758 consultants were randomly assigned to either use GPT-4 AI or not. As a result, consultants who used AI completed 12.2% more work on average and finished their tasks 25.1% faster. On top of that, quality also improved by over 40%.